Liquid cooled housing for rotary piston combustion engine

ABSTRACT

A rotary piston combustion engine has a housing of at least one shell and at least two parallel end parts. Each shell is arranged between the two end parts and they cooperate in defining an interior space in which a piston revolves. Each end part includes two end walls bounding a chamber traversed by cooling liquid; and the piston is fitted on its faces with axially movable gas and oil seals sliding along the neighboring faces of the end walls.

United States Patent Ruf Sept. 2, 1975 [54] LIQUID COOLED HOUSING FOR ROTARY 3,289,647 12/1966 Turner et al 418/83 X PISTON COMBUSTION ENGINE [75] Inventor: Max Ruf, Obereisesheim, Germany Primary Examiner-C. J. Husar [731 Assignees: Audi NS Auto Union Assistant Examinerl,eonard Smith Akfiengesenschaft; Wankel GmbH Attorney, Agent, or Firm-Kane, Dalsimer, Kane, both of Germany Sullivan and Kurucz [22] Filed: Mar. 6, 1974 [21] App]. No.: 448,642 [57] ABSTRACT A rotary piston combustion engine has a housing of at [30] Forelgn Apphcanon Pnomy Data least one shell and at least two parallel end parts. Each Mar. 8, 1973 Germany 2311371 she is arranged between the two end pans and they cooperate in defining an interior space in which a pis- [52] [1.8. Ci; 418/83 ton revolves Each end part includes two end walls [51] Int. Cl. F04C 29/04 bounding a Chamber traversed by cooling liquid; and [58] new of Search 418/83 61 A; 123/80] the piston is fitted on its faces with axially movable gas and oil seals sliding along the neighboring faces of the [56] References Cited end Walls UNITED STATES PATENTS 3,269,372 8/1966 Bonner 418/83 1 Claim, 2 Drawing Figures PATENTED SEP 2 I 75 saw 2 0F 2 LIQUID COOLED HOUSING FOR ROTARY PISTON COMBUSTION ENGINE BACKGROUND OF DISCLOSURE In known rotary piston combustion engines the end wall surfaces adjoining the interior space experience temperature differentials inside and outside the zone swept by the oil seals owing to the combustion process. Consequently in the case of a material of comparatively low heat conductivity, especially in the hot sector, adequate removal by the coolant is limited, so that stresses arise that may strain the end walls. Even with end parts with walls spaced apart by fins within the chamber traversed by the coolant, thermal stresses occur under the influence of high temperatures on the surface of the end walls; and this may cause a wavy distortion of the walls. Strained and wavy end parts have the disadvantage that the oil seals axially arranged in the face of the piston and sliding against such parts are unable to follow the unevenness with their sealing edges, so that they fail to make close contact, and lubricant is permitted to leak into the working chambers.

SUMMARY OF THE INVENTION The object of the invention is to provide end parts with walls in which strains that would normally cause leakage are largely avoided at least in the zone of the oil seals despite the differential temperatures acting upon them.

This objective is accomplished by providing the end part walls facing the piston with a greater wall thickness in the zone swept by the oil seals than in the remaining zone extending radially outwardly to the shell; and these walls are supported by fins exclusively in the vicinity of the adjoining shell.

In the proposed arrangement, the increased wall thickness serves to stiffen that portion of the end wall which is swept by the oil seals, so that the stresses due to temperature influences cannot lead to such thermal distortion of the end wall as to cause leakage at the oil seal. Furthermore, such a stiffening of the end wall may also counteract possible deformations that may arise in the assembly and from bolting of the housing. The zone radially outside the zone swept by the oil seals and bordering on the shell, and subjected to the greatest thermal stress, may instead have a wall thickness providing adequate heat transfer to the coolant, thus permitting optimum cooling of the end wall. Since the fins arranged to support the end walls are located exclusively in the vicinity of the shell, wavy deformation of the face is avoided. Thus the end walls may be bathed by coolant completely over the entire area and uniformly without interruption. The fins merely serve to withstand the tensions of the bolts connecting the end parts to the shell.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of an end part according to the invention is represented by way of example in the drawing.

FIG. 1 shows a section, in axial direction of a portion of a housing; and

FIG. 2 shows an elevation of the wall of an end piece viewed in direction A in FIG. 1 to a smaller scale.

DETAILED DESCRIPTION Referring initially to FIG. 1, an end part 1 (which may alternatively be an intermediate part) has two parallel walls 2 and 2a and in cooperation with a shell 3 in contact with its wall 2 and an additional end part (not shown) defines an enclosed interior space 4 in which revolves a piston 5. The piston includes axially movable gas seals 6 and oil seals 7 on its faces to slide along the adjacent face of end wall 2. The two walls 2 and 2a bound a chamber 8 traversed by coolant. In zone 10 radially within the outer envelope 9 of the oil seal 7 of the piston 5 revolving in the interior space 4, side wall 2 has a greater wall thickness for stiffening and rigidifying purposes than in the zone 11 extending radially outward to the shell 3 and adjacent for the most part to the working chambers. Fins 12 space the walls 2, 2a of end part 1, bounding the chamber 8 exclusively in the zone 13 of contact with the shell 3, so that zones 10 and 1] are completely bathed in coolant with no interruption by the fins.

FIG. 2 shows an elevation of wall 2 along with the outer envelope 9 of oil seal 7. In the zone 10 inside this envelope 9 the wall is thicker than in the thinner-walled zone 11, extending from the envelope 9 to the zone 13 bounded by the shell 3. The fins 12 supporting the walls of end part 1 are arranged exclusively in zone 13 (see FIG. 1).

Thus the several aforenoted objects and advantages are most effectively attained. Although several somewhat preferred embodiments have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.

What is claimed is:

1. A rotary piston combustion engine having a housing composed of at least one shell and at least two parallel end pieces, each shell being arranged between two end pieces and having an inner wall enclosing an interior space in which a piston revolves, each end'piece having an outer and an inner wall bounding a chamber traversed by coolant and the piston having axially movable gas and oil seals on its faces to slide along the neighboring faces of the inner walls of the end pieces, the inner wall of each end piece having a greater thickness in the zone swept by the oil seals than in the remaining radially adjoining zone outwards as far as the inner wall of the shell and is supported by fins exclusively in the zone of contact of the shell with the inner wall of the end piece. 

1. A rotary piston combustion engine having a housing composed of at least one shell and at least two parallel end pieces, each shell being arranged between two end pieces and having an inner wall enclosing an interior space in which a piston revolves, each end piece having an outer and an inner wall bounding a chamber traversed by coolant and the piston having axially movable gas and oil seals on its faces to slide along the neighboring faces of the inner walls of the end pieces, the inner wall of each end piece having a greater thickness in the zone swept by the oil seals than in the remaining radially adjoining zone outwards as far as the inner wall of the shell and is supported by fins exclusively in the zone of contact of the shell with the inner wall of the end piece. 